oh dang didn't realize the diff. models ha. 597DI and the 788 hd di

Brian, both of those units have the same display in screen brightness, size and pixel count. The highest resolution displays in the industry.with 31,170.5 pixels per square inch.

The 788ci HD DI can be linked to another Humminbird unit to share common data with Ethernet or Interlink, The 597ci HD DI cannot be linked to another unit.

The 788ci HD DI has two card readers for mapping and/or screen snapshots, recording, unit updates and waypoint management.

The 597ci HD DI has just one card reader but can do the same.

thanks wayne, didn't know the 597 could do the waypoints

brian, the whole model number for the 597 is 597ci HD DI Combo and the whole model number for the 788 is 788ci HD DI Combo

The 788 is the model series, the ( c ) is for color display, the ( i ) is for internal GPS antenna, the HD is for the screen resolution and model year, DI is for Down Imaging, and Combo is for a combinatiion of sonar and GPS functions.

Some units are Combo units but will come with an external GPS antenna so they won't have the ( i ) in the model number.

you've been very helpful wayne, appreciate all the info. relatively new with depthfinders and this saved me some money for sure!!